From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Upton Date: Mon, 5 Aug 2024 23:25:55 +0000 Subject: [PATCH v12 54/84] KVM: arm64: Mark "struct page" pfns accessed/dirty before dropping mmu_lock In-Reply-To: <20240726235234.228822-55-seanjc@google.com> References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-55-seanjc@google.com> Message-ID: List-Id: To: kvm-riscv@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit [+cc Fuad] Fuad, you mentioned in commit 9c30fc615daa ("KVM: arm64: Move setting the page as dirty out of the critical section") that restructuring around the MMU lock was helpful for reuse (presumably for pKVM), but I lack the context there. On Fri, Jul 26, 2024 at 04:52:03PM -0700, Sean Christopherson wrote: > Mark pages/folios accessed+dirty prior to dropping mmu_lock, as marking a > page/folio dirty after it has been written back can make some filesystems > unhappy (backing KVM guests will such filesystem files is uncommon, and typo: s/will/with/ > the race is minuscule, hence the lack of complaints). See the link below > for details. > > This will also allow converting arm64 to kvm_release_faultin_page(), which > requires that mmu_lock be held (for the aforementioned reason). > > Link: https://lore.kernel.org/all/cover.1683044162.git.lstoakes at gmail.com > Signed-off-by: Sean Christopherson > --- > arch/arm64/kvm/mmu.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 22ee37360c4e..ce13c3d884d5 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1685,15 +1685,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > } > > out_unlock: > + if (writable && !ret) > + kvm_set_pfn_dirty(pfn); I'm guessing you meant kvm_release_pfn_dirty() here, because this leaks a reference. > + else > + kvm_release_pfn_clean(pfn); > + > read_unlock(&kvm->mmu_lock); > > /* Mark the page dirty only if the fault is handled successfully */ > - if (writable && !ret) { > - kvm_set_pfn_dirty(pfn); > + if (writable && !ret) > mark_page_dirty_in_slot(kvm, memslot, gfn); > - } > > - kvm_release_pfn_clean(pfn); > return ret != -EAGAIN ? ret : 0; > } > > -- > 2.46.0.rc1.232.g9752f9e123-goog > -- Thanks, Oliver From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9C58416CD12 for ; Mon, 5 Aug 2024 23:26:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722900368; cv=none; b=E4My3DlENxALbaFKGoGQNHyMXg7UsCRK8yjqHNy+bHgZ9c9W1YiDk6fE3Dg90mCogF1Ety4JFkpSQnZbryNx3dBxa4baG66cpuk4ctRkGTbxaFwiVhYzS4wu4vCVEaozH/bvMhvMLGtgvl+s/le5fsxAGWkVA3wKLASghyybhzA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722900368; c=relaxed/simple; bh=NZCRFKbIN8PF8TtGzo0TuabedSFqMXcg0tKfwiHnKPs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=L5vJZejMRJbKuDrW07fAmHwyjOhK7HoDALlW2H2kimIOr4oZbT05mEv2+s15p/t/W1tAJ5w98tOB/a/MP4oYAtYoRfGjbo8SDV/APQ6HcHOZ/K2Pehagt+ABOPXLcujvjlknzw9/m8EQJGBmIkmN5Y+Q2Tez1vmfuZlRNVp2GEA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=nsqM4WvI; arc=none smtp.client-ip=91.218.175.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="nsqM4WvI" Date: Mon, 5 Aug 2024 23:25:55 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1722900362; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+mfeo2RqmDWupNPy1ZQ9DQzaW41XBFzcKm+dZAjG39w=; b=nsqM4WvIeqvYHal0R7bad4sl2RiCqdaEThtnF1PVGpbpIk6TP7/CSQ1lcdBlex5IzcKPCb 7g4CjFX6c6eUuhlGombjt0+/nOmNqPRG0qjhofrleHk8DYNXPAn7Q/OhxjYef93ialM8P+ YvQTTQKWBorXAs+vuLMxHvrpEon2vKo= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Sean Christopherson Cc: Paolo Bonzini , Marc Zyngier , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , David Stevens Subject: Re: [PATCH v12 54/84] KVM: arm64: Mark "struct page" pfns accessed/dirty before dropping mmu_lock Message-ID: References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-55-seanjc@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240726235234.228822-55-seanjc@google.com> X-Migadu-Flow: FLOW_OUT [+cc Fuad] Fuad, you mentioned in commit 9c30fc615daa ("KVM: arm64: Move setting the page as dirty out of the critical section") that restructuring around the MMU lock was helpful for reuse (presumably for pKVM), but I lack the context there. On Fri, Jul 26, 2024 at 04:52:03PM -0700, Sean Christopherson wrote: > Mark pages/folios accessed+dirty prior to dropping mmu_lock, as marking a > page/folio dirty after it has been written back can make some filesystems > unhappy (backing KVM guests will such filesystem files is uncommon, and typo: s/will/with/ > the race is minuscule, hence the lack of complaints). See the link below > for details. > > This will also allow converting arm64 to kvm_release_faultin_page(), which > requires that mmu_lock be held (for the aforementioned reason). > > Link: https://lore.kernel.org/all/cover.1683044162.git.lstoakes@gmail.com > Signed-off-by: Sean Christopherson > --- > arch/arm64/kvm/mmu.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 22ee37360c4e..ce13c3d884d5 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1685,15 +1685,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > } > > out_unlock: > + if (writable && !ret) > + kvm_set_pfn_dirty(pfn); I'm guessing you meant kvm_release_pfn_dirty() here, because this leaks a reference. > + else > + kvm_release_pfn_clean(pfn); > + > read_unlock(&kvm->mmu_lock); > > /* Mark the page dirty only if the fault is handled successfully */ > - if (writable && !ret) { > - kvm_set_pfn_dirty(pfn); > + if (writable && !ret) > mark_page_dirty_in_slot(kvm, memslot, gfn); > - } > > - kvm_release_pfn_clean(pfn); > return ret != -EAGAIN ? ret : 0; > } > > -- > 2.46.0.rc1.232.g9752f9e123-goog > -- Thanks, Oliver From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 95B50C3DA4A for ; Mon, 5 Aug 2024 23:26:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=vdXqk5i+PCWQIRevdVArFGmhBmnBoyM+RGiqoZOqBC4=; b=PtNnyOmhY2QPjH iZn02kzH4oecVIb5QaeqJRJhSSGEb7PAiBE6vgOvtyFajbLNg4syK1gQ9YYXfEzcTGqMG9urrzpIz 9RXQ59y51SpCJ+uhkJOydXULphzJMNu2HOJx/9cPNvZyMgo19uDCVhP8agtQjtc+AL8OPZMzsJp6n WNaqxxwqn2DzKbOTU4+rbEmgniiyimOdNOw2VAWo+oMjR35lh1UbmJoByfUGSPEXWsek4E+DjesJp ExNPWz581qYC8K8l2Qm91I/KZqDQk75tUYCp6n6va8JIjc6JcNeg9aic5NiXJNoY691Vsfxvo+d41 9ZLKTTiyB3grwiYwhiTQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sb75i-0000000HY1f-0NpA; Mon, 05 Aug 2024 23:26:14 +0000 Received: from out-177.mta0.migadu.com ([91.218.175.177]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sb75b-0000000HY0A-0v32 for linux-riscv@lists.infradead.org; Mon, 05 Aug 2024 23:26:11 +0000 Date: Mon, 5 Aug 2024 23:25:55 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1722900362; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+mfeo2RqmDWupNPy1ZQ9DQzaW41XBFzcKm+dZAjG39w=; b=nsqM4WvIeqvYHal0R7bad4sl2RiCqdaEThtnF1PVGpbpIk6TP7/CSQ1lcdBlex5IzcKPCb 7g4CjFX6c6eUuhlGombjt0+/nOmNqPRG0qjhofrleHk8DYNXPAn7Q/OhxjYef93ialM8P+ YvQTTQKWBorXAs+vuLMxHvrpEon2vKo= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Sean Christopherson Cc: Paolo Bonzini , Marc Zyngier , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , David Stevens Subject: Re: [PATCH v12 54/84] KVM: arm64: Mark "struct page" pfns accessed/dirty before dropping mmu_lock Message-ID: References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-55-seanjc@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240726235234.228822-55-seanjc@google.com> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240805_162607_566622_072B16E4 X-CRM114-Status: GOOD ( 18.08 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org [+cc Fuad] Fuad, you mentioned in commit 9c30fc615daa ("KVM: arm64: Move setting the page as dirty out of the critical section") that restructuring around the MMU lock was helpful for reuse (presumably for pKVM), but I lack the context there. On Fri, Jul 26, 2024 at 04:52:03PM -0700, Sean Christopherson wrote: > Mark pages/folios accessed+dirty prior to dropping mmu_lock, as marking a > page/folio dirty after it has been written back can make some filesystems > unhappy (backing KVM guests will such filesystem files is uncommon, and typo: s/will/with/ > the race is minuscule, hence the lack of complaints). See the link below > for details. > > This will also allow converting arm64 to kvm_release_faultin_page(), which > requires that mmu_lock be held (for the aforementioned reason). > > Link: https://lore.kernel.org/all/cover.1683044162.git.lstoakes@gmail.com > Signed-off-by: Sean Christopherson > --- > arch/arm64/kvm/mmu.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 22ee37360c4e..ce13c3d884d5 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1685,15 +1685,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > } > > out_unlock: > + if (writable && !ret) > + kvm_set_pfn_dirty(pfn); I'm guessing you meant kvm_release_pfn_dirty() here, because this leaks a reference. > + else > + kvm_release_pfn_clean(pfn); > + > read_unlock(&kvm->mmu_lock); > > /* Mark the page dirty only if the fault is handled successfully */ > - if (writable && !ret) { > - kvm_set_pfn_dirty(pfn); > + if (writable && !ret) > mark_page_dirty_in_slot(kvm, memslot, gfn); > - } > > - kvm_release_pfn_clean(pfn); > return ret != -EAGAIN ? ret : 0; > } > > -- > 2.46.0.rc1.232.g9752f9e123-goog > -- Thanks, Oliver _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A85D0C3DA7F for ; Mon, 5 Aug 2024 23:33:34 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=nsqM4WvI; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4WdCRx23rBz3cbF for ; Tue, 6 Aug 2024 09:33:33 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=nsqM4WvI; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.dev (client-ip=91.218.175.187; helo=out-187.mta0.migadu.com; envelope-from=oliver.upton@linux.dev; receiver=lists.ozlabs.org) X-Greylist: delayed 373 seconds by postgrey-1.37 at boromir; Tue, 06 Aug 2024 09:32:50 AEST Received: from out-187.mta0.migadu.com (out-187.mta0.migadu.com [91.218.175.187]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4WdCR63b3wz3cK8 for ; Tue, 6 Aug 2024 09:32:50 +1000 (AEST) Date: Mon, 5 Aug 2024 23:25:55 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1722900362; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+mfeo2RqmDWupNPy1ZQ9DQzaW41XBFzcKm+dZAjG39w=; b=nsqM4WvIeqvYHal0R7bad4sl2RiCqdaEThtnF1PVGpbpIk6TP7/CSQ1lcdBlex5IzcKPCb 7g4CjFX6c6eUuhlGombjt0+/nOmNqPRG0qjhofrleHk8DYNXPAn7Q/OhxjYef93ialM8P+ YvQTTQKWBorXAs+vuLMxHvrpEon2vKo= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Sean Christopherson Subject: Re: [PATCH v12 54/84] KVM: arm64: Mark "struct page" pfns accessed/dirty before dropping mmu_lock Message-ID: References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-55-seanjc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240726235234.228822-55-seanjc@google.com> X-Migadu-Flow: FLOW_OUT X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Matlack , linux-riscv@lists.infradead.org, Claudio Imbrenda , Marc Zyngier , Janosch Frank , Huacai Chen , Christian Borntraeger , Albert Ou , Bibo Mao , loongarch@lists.linux.dev, Paul Walmsley , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, Palmer Dabbelt , David Stevens , kvm-riscv@lists.infradead.org, Anup Patel , Paolo Bonzini , Tianrui Zhao , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" [+cc Fuad] Fuad, you mentioned in commit 9c30fc615daa ("KVM: arm64: Move setting the page as dirty out of the critical section") that restructuring around the MMU lock was helpful for reuse (presumably for pKVM), but I lack the context there. On Fri, Jul 26, 2024 at 04:52:03PM -0700, Sean Christopherson wrote: > Mark pages/folios accessed+dirty prior to dropping mmu_lock, as marking a > page/folio dirty after it has been written back can make some filesystems > unhappy (backing KVM guests will such filesystem files is uncommon, and typo: s/will/with/ > the race is minuscule, hence the lack of complaints). See the link below > for details. > > This will also allow converting arm64 to kvm_release_faultin_page(), which > requires that mmu_lock be held (for the aforementioned reason). > > Link: https://lore.kernel.org/all/cover.1683044162.git.lstoakes@gmail.com > Signed-off-by: Sean Christopherson > --- > arch/arm64/kvm/mmu.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 22ee37360c4e..ce13c3d884d5 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1685,15 +1685,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > } > > out_unlock: > + if (writable && !ret) > + kvm_set_pfn_dirty(pfn); I'm guessing you meant kvm_release_pfn_dirty() here, because this leaks a reference. > + else > + kvm_release_pfn_clean(pfn); > + > read_unlock(&kvm->mmu_lock); > > /* Mark the page dirty only if the fault is handled successfully */ > - if (writable && !ret) { > - kvm_set_pfn_dirty(pfn); > + if (writable && !ret) > mark_page_dirty_in_slot(kvm, memslot, gfn); > - } > > - kvm_release_pfn_clean(pfn); > return ret != -EAGAIN ? ret : 0; > } > > -- > 2.46.0.rc1.232.g9752f9e123-goog > -- Thanks, Oliver